Camera3dBundle doesn't render anything when looking from above

[dmyyy]

Bevy version

0.9.1

[Optional] Relevant system information

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AdapterInfo { name: "NVIDIA GeForce RTX 3080", vendor: 4318, device: 8710, device_type: DiscreteGpu, driver: "NVIDIA", driver_info: "528.49", backend: Vulkan }

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What you did

Minimal code example demonstrating the issue:

use bevy::prelude::*;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_startup_system(setup)
        .run();
}

fn setup(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    commands.spawn(Camera3dBundle {
        transform: Transform::from_xyz(0., 5., 0.).looking_at(Vec3::new(0.0, 0.0, 0.0), Vec3::Y),
        ..default()
    });

    // plane
    commands.spawn(PbrBundle {
        mesh: meshes.add(Mesh::from(shape::Plane { size: 5.0 })),
        material: materials.add(Color::rgb(0.3, 0.5, 0.3).into()),
        ..default()
    });

    commands.spawn(PbrBundle {
        mesh: meshes.add(Mesh::from(shape::Cube { size: 1.0 })),
        material: materials.add(Color::rgb(0.8, 0.7, 0.6).into()),
        transform: Transform::from_xyz(0.0, 0.5, 0.0),
        ..default()
    });
}

When you change from_xyz(0., 5., 0.) to from_xyz(0., 5., 1.) you see everything fine. Expected to see an overhead view with from_xyz(0., 5., 0.) - instead got a gray screen.

Additional information

Other information that can be used to further reproduce or isolate the problem.
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• screenshots
• logs
• theories about what might be going wrong
• workarounds that you used
• links to related bugs, PRs or discussions

[tim-blackbird]

The issue is that the transform position and both arguments to looking_at are on the same line. This does not give enough information to construct a rotation.
See #6136 for more discussion.

[alice-i-cecile]

I've reproduced this in my own games. I'm not a fan of how it silently fails.